General :: Create A Softlink To Move Some Library Folder?

I'm running out of disk space in root, so I decide to move /usr/lib64 directory to other partition by creating moving the whole directory to new location and create a softlink in the old location. What I'm planning to do is:

1. Copy the whole directory to new location

2. Make sure if there's no problem in the copy process

3. Create a softlink in the old location pointing to the new location.

However, when I'm comparing the old location and the new location using du command, there's some discrepancies between those two where the new location contain bigger size than the old one. How is this possible?

Is this the proper way to save disk space by creating a softlink?